Siemens SIMATIC NET PROFIBUS Operations Instructions download pdf (Page 32)

Product Characteristics

4.2 Installation

SIMATIC NET PROFIBUS Optical Link Module OLM V4.0

26 Operating Instructions, 01/2013, C79000-G8976-C270-03

4.2.3.6 Reducing the optical transmit power

Notice! The following information is only valid for the default setting of S7 (S7=0)!

for OLM / P11, OLM / P12, and OLM / P22

The OLM / P11, OLM / P12, and OLM / P22 have a high optical transmit power. Connecting

these modules with non-OLM devices via plastic fiber-optic cables can lead to optical

overdrive, especially if short cables are used. In this case, the optical transmit power can be

reduced by approx. 60% (3.8 dB).

for OLM / G11, OLM / G12, OLM / G12 EEC and OLM / G22

The OLM / G11, G12, G12 EEC and OLM / G22 have a high optical transmit power.

Connecting these modules with non-OLM devices via multimode fiber-optic cables can lead

to optical overdrive, especially if short cables are used. In this case (revision 04 and higher

for OLM / G11, G12, G12 EEC and OLM / G22), the optical transmit power can be reduced

by approx. 70% (4.5 dB).

The valid revision (rev) is marked with an "X" on the type plate.

For e.g.

for rev = 04.

The optical transmit power of CH2 is set with DIL switch S5.

The optical transmit power of CH3 is set with DIL switch S6.

S6 has no function for the OLM / P11 and OLM / G11, respectively.

Leave S5 in position 1 (default) if the fiber-optic link on CH2 works correctly in this position.

Leave S6 in position 1 (default) if the fiber-optic link on CH3 works correctly in this position.

Set S5 to position 0 (reduced) if overdrive of a non-OLM device occurs on CH2.

Set S6 to position 0 (reduced) if overdrive of a non OLM-device occurs on CH3.

Note

When using PCF fibers, the default transmit power must be set (S5 or S6 in position 1).

Note

If OLM / P11 V4.0, OLM / P12 V4.0, or OLM / P22 V4.0 is operated along with OBTs, IM151-

1 FO, CP 5613 FO/CP 5614 FO, IM 467 FO, CP 342-5 FO or IM 153-2 FO devices using S

980/1000 plastic fiber cables, the devices must be interconnected by fiber-optic cables with a

minimum length of 30 m (see Figure 4-2). As an alternative, a fixed attenuator with an

attenuation value between 5 dB and 15 dB can be used. The fixed attenuator must be

installed into the OLM receiver line. The coresponding DIL switch (S5 or S6) has to be set to

"reduced". If PCF fibers S 200/230 are used, neither a minimum line length nor an attenuator

is necessary.

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Siemens SIMATIC NET PROFIBUS Operations Instructions Page 32